An easy way to run multiple instances of any program
Apr 11, '08 07:30:01AM • Contributed by: Jeremy Banks

I've seen a few tips on different sites explaining how to run two copies of certain applications. Most of these involve creating a second copy of the Application bundle, which can be impractical if it contains too many resources, and is a hassle in any case.

Here's an easier way that I don't think anyone has posted here: Just run the application that you'd like to launch a second time from Terminal, using the open command with the --new (-n) flag. This will force an additional instance to be opened regardless of how many are already running. For example, if I wanted to run another copy of Mail, I'd do it this way:

open -n /Applications/Mail.app

Remember that you can drag an icon to the Terminal window and it will insert its path, making this even simpler!

[robg adds: We've run a couple of hints on running multiple copies of the same application. This one used an AppleScript for Remote Desktop Connection 2.0, but could be extended for other applications. This much older hint used a Terminal command to find the actual application executable. Note that running multiple copies of one app as the same user may not work perfectly, especially if the app requires exclusive access to a file, or if you change preferences while two copies are running.]

An easy way to run multiple instances of any program
Authored by: Brock Lee on Apr 11, '08 01:35:21PM

As a general stance, I would be cautious about using this hint. Multiple running instances of a program may be accessing and modifying the very same configuration files simultaneously, resulting in potential race conditions and file corruption.

An easy way to run multiple instances of any program
Authored by: marksch on Sep 29, '11 01:56:29PM

Although this may be true for some apps, other apps are perfectly well suited for running as multiple instances. Don't let cautiousness keep you from conveniently running the same copy of an app multiple times.

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Mark

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